Polychrest \Pol"y*chrest\, n. [Gr. ? useful for many purposes; poly`s many + ? useful, fr. ? to use: cf. F. polychreste.] (Med.) A medicine that serves for many uses, or that cures many diseases. [Obs.] [1913 Webster] {Polychrest salt} (Old Med. Chem.), potassium sulphate, specifically obtained by fusing niter with sulphur. [1913 Webster]